Method for making cases for firearms

ABSTRACT

Described is a A method for making cases for firearms of the type comprising including a substantially cylindrical rigid pipe (2), a plastically deformable reinforcing element (6) and pre-shaped with a perimeter anchoring tooth (15), and a substantially cylindrical rigid base (7), which has a tubular side wall (8) and a bottom wall (9) along whose perimeter edge (10) the side wall (8) is flared outwards in such a way as to form a collar (11) which has internally a seat undercut; the. The method comprises includes inserting the reinforcing element (6) in the pipe (2), and both in the base (7) until they make contact the bottom wall (9) of the base (7); and axially compressing the reinforcing element (6) such a way that, by deforming plastically, it expands radially until securing the pipe (2) against the inner side wall (8) of the base (7), and until inserting the anchoring tooth (15) inside the collar (11) with the consequent radial deformation of an end edge (5) of the pipe (2), which is thus secured, in flared configuration, between the anchoring tooth (15) and the collar (11).

TECHNICAL FIELD

This invention relates to a method for making cases for firearms.

BACKGROUND ART

The cases for firearms are traditionally made by assembling in a mutually integral manner three elements:

-   -   a rigid pipe, made of plastic or paper;     -   a base made of rigid metallic material; and     -   a reinforcing element made of deformable material, either         plastic or paper, and known to experts in the field as “base         wad”.

The pipe is substantially cylindrical in shape, with its longitudinal end folded towards the inside, that is to say, towards the axis, in such a way as to define an annular edge.

The body has a substantially cylindrical shape, with a tubular side wall and a bottom wall.

Along the perimeter edge of the bottom wall, the side wall is flared outwards in such a way as to form a so-called “collar” which has internally a seat undercut.

The bottom wall has a central hole through which an ignition capsule is inserted for triggering the gunpowder.

The reinforcing element is externally cylindrical and has a head end with a depression for defining a cup for containing the gunpowder.

On the opposite side of the cup the reinforcing element has a bottom wall which has a central hole leading into the cup and designed to be coaxial with the hole of the base for housing the ignition capsule.

The assembling comprises, in sequence:

-   -   inserting the reinforcing element in the pipe until bringing it         into contact with the above-mentioned annular edge;     -   inserting the pipe into the base until the annular edge is in         contact with the bottom wall of the base; and     -   compressing the reinforcing element in such a way that, when         deforming, on one side it pushes the pipe against the inner side         wall of the base and, on the other side, it radially deforms the         folded end of the pipe which defines the annular edge, blocking         the end inside the above-mentioned collar.

The compression of the reinforcing element constitutes the most critical and delicate step of the assembly process.

In effect, to prevent the pipe, at the moment of firing, from coming out of the base and entering, dangerously, in the barrel of the rifle, it is necessary to exert on the reinforcing element a considerable mechanical stress, such as to plastically deform the reinforcing element and the pipe inside the collar.

Basically, the reinforcing element and the pipe are deformed to form, inside the collar, a so-called “anchoring tooth”.

The process, if not controlled correctly, may however cause serious consequences.

Firstly, a non-uniform forming of the anchoring tooth, due for example to a partial elastic return of the reinforcing element, may result in the serious disassembly of the three elements of the case after firing.

Moreover, if a compression is applied on the reinforcing element with an intensity greater than planned, this may result in an excessive flattening of the pipe with a consequent weakening to the traction and, consequently, insufficient resistance during firing.

It should also be noted that, in order to obtain compression forces which are carefully controlled and with an intensity such as to plastically deform the reinforcing element and the pipe inside the collar, it is necessary use machines which are technically complex and high powered.

In order to overcome the above-mentioned drawbacks, cases with three elements have also been proposed wherein the reinforcing element is also rigid and substantially non-deformable. In this case, the reinforcing element is pre-shaped in such a way as to have the anchoring tooth already before assembly and it is not subjected to any mechanical compression stress during assembly, and the base, open at the bottom, is folded around the anchoring tooth by hemming, rolling or the like, to make the collar around the tooth.

However, this solution requires machines which are just as complex due to the above-mentioned step of folding the open base.

DISCLOSURE OF THE INVENTION

The aim of this invention is to provide a method for making cases for firearms which is free of the above-mentioned disadvantages.

This aim is fully achieved by the method according to this invention as characterised in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical features and advantages of the invention are more apparent in the following description of a preferred embodiment of it, illustrated by way of non-limiting example in the accompanying drawings, in which:

FIG. 1 shows the pipe, the reinforcing element and the base of a case to be assembled with the method according to this invention;

FIG. 2 is a perspective view of the reinforcing element FIG. 1;

FIG. 3 shows the pipe, the reinforcing element and the base of FIG. 1 after their assembly; and

FIGS. 4 and 5 are two different views of a variant of the reinforcing element shown in FIGS. 1, 2 and 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

With reference to FIGS. 1 and 3, the numeral 1 denotes in its entirety a case for firearms comprising:

-   -   a substantially cylindrical pipe 2, made of a rigid material and         delimited, at its first longitudinal end 4, by a substantially         circular end edge 5;     -   a reinforcing element 6, made of plastically deformable material         and inserted inside the first end 4 of the pipe 2; and     -   a base 7, made of a rigid material, fitted on the first end 4 of         the pipe 2 and having a substantially cylindrical shape, with a         tubular side wall 8 and with a bottom wall 9 along whose         perimeter edge 10 the side wall 8 is flared outwards in such a         way as to form a collar 11 which has internally a seat undercut.

The pipe 2 is preferably made of plastic material or paper and is substantially non-deformable. The inside of the pipe 2 houses the gunpowder, not illustrated. On the opposite side of the first end 4, that is to say, at its second longitudinal end, the pipe 2 holds a projectile, also not illustrated.

The base 7 is preferably made of metal material and FIG. 1 illustrates it for simplicity in a configuration of use.

In reality, during the assembly, there is a spaced apart configuration also at the collar 11 and it is compressed in the configuration illustrated once the case is completed.

The bottom wall 9 of the base 7 has a central hole 9 a through which, in a substantially known manner, a striker may acting on an ignition capsule.

The reinforcing element 6 is preferably made of plastic material, and is known to experts in the field as “base wad”.

The reinforcing element 6 is pre-shaped with a substantially cylindrical side wall 12 and with a bottom wall 13 along whose perimeter edge 14 the side wall 12 is flared outwards in such a way as to form a perimeter anchoring tooth 15.

The pre-shaping of the reinforcement element 6 is preferably obtained using a pressing operation.

As illustrated better in FIG. 2, the reinforcing element 6 has a head end 16 with a depression for defining a cup 17 for containing the gunpowder.

On the opposite side of the cup 17, that is to say, on the bottom wall 13, the reinforcing element 6 has a central hole 13 a leading to the cup.

The hole 13 a is designed to house an ignition capsule, not illustrated, to trigger the gunpowder.

Under the cup 17, the side wall 12 of the reinforcing element 6 has an annular groove 18, that is to say, a perimeter groove 18.

The annular groove 18 is flared towards the outside of the reinforcement element 6. More specifically, the transversal cross section of the annular groove 18 has a substantially triangular shape.

The groove 18 is defined by the extension in a cantilever fashion of the annular peripheral portion 17 a of the bottom wall of the cup 17.

When the case 1 is assembled, the reinforcing element 6 is positioned closely inside in the pipe 2 with the tooth 15 substantially flush with the above-mentioned edge 5 of the pipe 2.

More specifically, the pipe 2 is clamped between the wall 12 which delimits peripherally the cup 17 and the side wall 8 of the base 7.

The bottom wall 13 of the reinforcing element 6 is in contact with the bottom wall 9 of the base 7.

The bottom wall 13 of the reinforcing element 6 has a central circular protrusion 19 which is contained tightly and flush inside the central hole 9 a of the bottom wall 9 of the base 7.

Both the tooth 15 and the edge 5 of the pipe 2 are positioned in contact with the bottom wall 9 of the base 7 and both are arranged tightly inside the collar 11.

More specifically, the edge 5 of the pipe 2 is clamped, in a flared configuration, between the tooth 15 and the collar 11.

The method for assembling the case (1) comprises:

-   -   inserting the reinforcing element 6 into the pipe 2 until the         anchoring tooth 15 is brought substantially flush with the end         edge 5 of the first end 4 of the pipe 2;     -   inserting the pipe 2 and the reinforcing element 6 into the base         7 until the edge 5 and the bottom wall 13 of the reinforcing         element 6 are brought into contact with the bottom wall 9 of the         base 7; and, after having positioned the three elements and         having retained them correctly in position;     -   axially compressing the reinforcing element 6 in such a way that         by deforming plastically, it expands radially until securing the         pipe 2 against the inner side wall 8 of the base 7, and until         inserting the anchoring tooth 15 inside the collar 11 with the         consequent radial deformation of the edge 5, which is thus         secured, in flared configuration, between the anchoring tooth 15         and the collar 11.

In a substantially known manner, the base is tightened about the pipe 2 and the reinforcing element 6 as well as flattened axially at the collar 11.

In other words, thanks to the fact that the reinforcing element 6 is pre-shaped with the tooth 15 and with the groove 18, is plastically deformable, its axial compression results in:

-   -   insertion of the tooth 15 inside the collar 11 with the radial         deformation of the edge 5 of the pipe 2 which is also forced         inside the collar 11;     -   the securing of the pipe 2 on the side wall 8 of the base 7;     -   the partial bending of the above-mentioned wall 17 a, that is to         say, the partial plastic yielding of the cup 17 which,         expanding, completes and increases the seal of the pipe 2 on the         side wall 8 of the base 7.

In other words, the step of axially compressing the reinforcing element 6 determines a partial flattening of the groove 18 with consequent radial expansion of the cup 17 and securing of the pipe 2 against the side wall 8 of the base 7.

It should be noted that, after firing, the bottom wall 17 a of the cup 17 bends further, thus further increasing the seal of the pipe 2 on the side wall 8 of the base 7.

The compression force is reduced compared with that of the prior art because it is not necessary to form by compression an anchoring tooth but simply expand inside the collar 11 the one already pre-shaped.

It should be noted in this regard that the dimensions of the reinforcing element 6, imparted during the making of the element 6, are specified to take into account its plastic radial expansion following the axial compression.

It should also be noted that the axial compression is sufficient to plastically bend the bottom wall 17 a of the cup 17, and thus expand the cup 17, and, thanks to the retaining action of the latter, which is completed after firing, there is a safe and reliable assembly.

It should also be noted that, unlike the prior art, the first longitudinal end of the pipe need not be folded towards the inside, that is to say, towards the axis, in such a way as to form an annular edge to be interposed between the bottom walls of the reinforcing element and the base. The absence of this folding operation advantageously simplifies the production process, making it faster and more economical.

It should also be noted that the method according to the invention is also advantageous relative to the prior art solutions wherein the reinforcing element, provided with a pre-shaped tooth, is substantially non-deformable and the base, which is open at the bottom, is folded around the anchoring tooth by hemming, rolling or the like, to make the collar around the tooth.

Also in this case, the absence of this operation of hemming, rolling or the like advantageously simplifies the production process, making it faster and more economical.

Lastly, it should be noted that, since the reinforcing element 6, already pre-shaped, does not require significant deformations and excessively high compression forces, it may be made with various geometrical shapes optimised for the firing functionality.

FIGS. 4 and 5 show, in this regard, a variant 6′ of the reinforcing element 6 shown in FIGS. 1, 2 and 3, which is also able to ensure the advantages described above. This variant adopts, denoted by a superscript, the same reference numerals as the reinforcing element 6, and for this, which differs mainly in the shape, reference should be made to the method for making described above.

The main difference of the variant 6′ is the presence of a plurality of protrusions 20′ positioned at the bottom of the cup 17′, the purpose of which is to prevent the gunpowder from suffocating the flame generated by the ignition capsule.

The invention described above is susceptible of industrial application and may be modified and adapted in several ways without thereby departing from the scope of the inventive concept. Moreover, all the details of the invention may be substituted for technically equivalent elements. 

1. A method for making cases for firearms of the type comprising: a substantially cylindrical pipe, made of a rigid material and delimited, at its first longitudinal end, by a substantially circular end edge; a reinforcing element, made of plastically deformable material and inserted inside the first end of the pipe; and a base, made of a rigid material, fitted on the first end of the pipe and having a substantially cylindrical shape, with a tubular side wall and with a bottom wall along whose perimeter edge the side wall of the base is flared outwards in such a way as to form a collar which has internally a seat undercut; the method being characterised in providing for the reinforcing element to be pre-shaped with a substantially cylindrical side wall and with a bottom wall along whose perimeter edge the side wall of the reinforcing element is flared outwards in such a way as to form a side anchoring tooth; and also being characterised in that it comprises the steps of: inserting the reinforcing element into the pipe until the anchoring tooth is brought substantially flush with the end edge of the first end of the pipe; inserting the pipe and the reinforcing element into the base until the end edge of the first end of the pipe and the bottom wall of the reinforcing element are brought into contact with the bottom wall of the base; and axially compressing the reinforcing element in such a way that by deforming plastically, it expands radially until securing the pipe against the inner side wall of the base, and until inserting the anchoring tooth inside the collar with the consequent radial deformation of the end edge of the first end of the pipe, which is thus secured, in flared configuration, between the anchoring tooth and the collar.
 2. The method according to claim 1, wherein the reinforcing element has a head end with a depression for defining a cup for containing the gunpowder, and wherein, below the cup, the side wall of the reinforcing element has an annular groove; the step of axially compressing the reinforcing element determining a partial flattening of the groove with consequent radial expansion of the cup and securing of the pipe against the side wall of the base.
 3. The method according to claim 1, wherein the reinforcing element has a head end with a depression for defining a cup for containing the gunpowder; the cup having a bottom wall, below which the side wall of the reinforcing element has an annular groove; the groove being defined by the extension, in cantilever fashion, of an annular peripheral portion of the bottom wall of the cup; the step of axially compressing the reinforcing element determining a partial bending of the annular peripheral portion of the bottom wall of the cup with consequent radial expansion of the cup and securing of the pipe against the inner side wall of the base.
 4. A case for firearms comprising a substantially cylindrical rigid pipe, a plastically deformable reinforcing element and pre-shaped with a perimeter anchoring tooth, and a substantially cylindrical rigid base, which has a tubular side wall and a bottom wall along whose a perimeter edge the side wall is flared outwards in such a way as to form a collar which has internally a seat undercut; the reinforcing element being inserted into the pipe, and both in the base, the reinforcing element and the pipe being in contact with the bottom wall of the base, the reinforcing element being compressed axially in such a way as to be expanded radially until securing the pipe against the inner side wall of the base, the anchoring tooth being inserted inside the collar, an end edge of the pipe being radially deformed and secured, in flared configuration, between the anchoring tooth and the collar. 